The present invention generally relates to disinfection of medical instruments using ozone.
Analysis of biological material is often performed by thinly slicing the material so that it can be viewed under a microscope. Various devices are employed for making the thin tissue samples, such as razor blades and microtome instruments. The material can be prepared for cutting by embedding the it in a supportive matrix, such as a paraffin based matrix, and then freezing the matrix and embedded biological material. The frozen matrix and embedded material cut, such as by the microtome to produce thin sections, which can then be stained and placed on a microscope slide for subsequent viewing.
A cryostat is an apparatus that provides a low-temperature environment and, accordingly, is widely used in the health care industry to freeze biological samples for later analysis. Microtomes and cryostats have been combined, producing an apparatus that can maintain biological samples in a frozen state, while thinly slicing them for examination.
During use, a cryostat and microtome may process biological samples from many different sources. To prevent contamination from sample to sample, it is desirable to periodically clean and disinfect the microtome and/or cryostat chamber. Similarly, the microtome and cryostat chamber must be cleaned and disinfected to prevent contamination from naturally occurring viruses, bacteria, and spores. Furthermore, disinfection of the microtome and cryostat chamber reduces the infection risk to operators from the biological samples.
Ozone is a known disinfecting agent that is effective in killing bacteria that are otherwise resistant to antibiotics. Ozone (O3) in a gaseous state can diffluse through an entire enclosure, disinfecting all surfaces within the space. However, ozone also tends to be chemically unstable, readily converting to oxygen (O2). Furthermore, ozone is toxic to humans when inhaled in high concentrations. These disadvantages have limited the use of ozone as a disinfecting agent in certain applications.
To overcome the problems with using ozone to disinfect medical equipment, it is known to employ water containing dissolved ozone. One method disinfects medical equipment by soaking the equipment in water containing sufficiently high amounts of dissolved ozone. Another method circulates water containing dissolved ozone around medical equipment. However, water containing dissolved ozone cannot be used to disinfect a cryostat chamber and microtome because the low temperatures typically present in the cryostat can freeze the water. Warming the cryostat chamber and microtome for disinfection with ozone-containing water is unfeasible because of the extensive processing time required to warm sterilize, and re-cool the cryostat.
Accordingly, there is a need for an apparatus and method to employ ozone to disinfect a cryostat and an associated microtome.
The present invention alleviates to a great extent the disadvantages of the known apparatus and methods for disinfecting medical instruments such as microtomes and cryostats by providing an enclosure that employs ozone for disinfection. In a preferred embodiment, the present invention includes a cryostat with an enclosable chamber, a pump, an ozone generator generating ozone, and an ozone destroyer.
In one embodiment, the pump creates a slight vacuum to verify the integrity of the cryostat chamber. The ozone generator creates ozone from oxygen present in the cryostat chamber air. The ozone diffuses through the cryostat chamber, disinfecting the microtome and chamber. After decontamination, the pump flushes the air/ozone from the cryostat chamber to the ozone destroyer. The ozone destroyer eliminates any remaining ozone.
In another embodiment of the present invention, a three-way valve directs the output of the pump. By regulating the output of the pump, the three-way valve controls the process of decontamination. In another embodiment of the invention, a second pump is employed. Ozone is created outside the cryostat chamber and the second pump directs the ozone into the cryostat chamber or to the ozone destroyer. If the first pump fails, the second pump directs the air/ozone to the ozone destroyer. In this way, any ozone in the cryostat chamber is eliminated, even if the first pump fails.
In another embodiment of the invention, a secondary power source is provided to supply backup power in case of a primary power failure. In yet another embodiment of the invention, a safety mechanism locks the cryostat chamber to prevent opening of the chamber during ozone decontamination.
These and other features and advantages of the present invention will be appreciated from review of the following detailed description of the invention, along with the accompanying figures in which like reference numerals refer to like parts throughout.